Energy storage devices such as ultracapacitors may be used in a variety of applications where a discrete power pulse is required. Such applications range from cell phones to hybrid vehicles. Ultracapacitors can include two or more carbon-based electrodes separated by a porous separator and an organic electrolyte. The foregoing active components can be arranged in a variety of designs, which can include parallel plate and jellyroll configurations. The active components are contained within a housing or package.
Important characteristics of an ultracapacitor are the energy density and the power density that it can provide. The energy density and the power density are largely determined by the properties of the active components. A further important characteristic is cost. Factors that impact the cost of the device include the cost of the raw materials, as well as the direct and indirect costs of the associated packaging, which can impact performance, manufactureabilty and reliability. It is desirable to make an ultracapacitor package simple and inexpensive while simultaneously robust and efficient.
One aspect of an ultracapacitor package is the means by which internal electrical connections are made. Approaches for forming electrical connections between the active components of the device (e.g., jellyroll) and the package terminals include welding, crimping and interference fits. Conventional designs that utilize the foregoing approaches, however, can have issues with long-term performance and reliability.
In view of the foregoing, there is a need for a simple, economical and robust package design for ultracapacitors.